Quenching bath for hardening and tempering rock drills



July 6, 1937. BEDFQRD 2,086,114

QUENCHING BATH FOR HARDENING A ND TEMPERING ROCK DRILLS Filed July 16,1936 3 Sheets-Sheet 1' Fig.4

July 6, 1937.

R. BEDFORD v QUENCHING BATH FOR HARDENING AND TEMPERING ROCK DRILLSFiled July 16, 1936 s Sheets-Sheet 2 y 6, 1937. R. A. BEDFORD 2,086,114

QUENCHING BATH FOR HARDENING AND TEMPERING ROCK DR ILLS Filed July 16,1936 3 Sheets-Sheet 3 Patented July 6, 1937 STA r orrice Reginald AslineRedford, Stumperlowe, Shefileld,

England Application July 16, 1936, Serial No. 90,851 In the Union ofSouth Africa March 9, 1936 5 Claims.

This invention relates to an improved quenching bath for hardening andtempering rock drills as used in mining and like operations and isparticularly applicable to the use of oil as the quenching fluidalthough it is by no means limited to its use with this medium.

A known type of quenching bath for this purpose comprises a tank havinga perforated removable false bottom for supporting the drills in theirimmersed positions, and having means for drawing off the surface liquidsuch as overflow outlet pipes connected adjacent the top edge thereof.Cold liquid is introduced into the bath at two or three points at ornear the bottom and the supply is regulated. It is well known to thoseskilled in the art, that the correct temperature of the fluid in thequenching bath is a most important factor in securing the requireddegree of hardness in drill steel. The known type of quenching bathabove referred to, owing to the uneven distribution of the quenchingfluid, does hot secure a uniform surface temperature. One of the mainobjects of the present invention is to provide a quenching bath in whicha substantially uniform surface temperature can be maintained, withmeans for regulating this temperature to suit the particular class ofdrill steel being treated.

According to this invention the improved quenching bath for hardeningand tempering rock drills comprises an inner quenching bath forcontaining quenching fluid located in an outer overflow container inspaced relation thereto, a perforated drill supporting plate removablysupported in the bath and adapted to determine the extent of immersionof the drills in the bath, means for holding the drills, and means forwithdrawing quenching fluid from the outer container and conveying it tothe bath in a closed circuit including a pump and cooling means.

The holding means may include a plurality of permanent magnets adaptedto magnetically hold the drills.

The quenching fluid, in circulating through the outer container and theinner bath, is conducted through a coil which is located exteriorly ofthe outer container and exposed to a cooling action.

Referring to the drawings filed therewith:- Fig. 1 is a sectionalelevation of one form of quenching bath made in accordance with thisinvention;

Fig. 2 is a plan of same, parts being omitted for clearness;

Fig. 3 is a sectional end elevation of Fig. 1;

Figs. 4 and 5 are detail views of the magnetic holding means for thedrills.

2 is an inner container, constituting the quenching bath proper, whichis dis sed inside of an outer larger container 3. The inner container 2is of substantial volume and is provided adjacent its top edge with aforaminous false bottom Ll for supporting the drills 5, which isadjustable as regardsits distance below said top edge. The top edge ofthe inner container is in the form of a'continuous dead level knife edgewhich forms a sill G across which the quenching fluid overflows into theouter container 3 after welling up through said false bottom, the innercontainer 2 being disposed in the middle of the outer container 3 sothat it is spaced therefrom and is surrounded on all sides for a portionof its height, by the quenching fluid which overflows across the sill 6.

The quenching fluid circulates in a closed circuit including a pump 1and a cooling coil 8 immersed in a tank of water, being deliveredthrough pipe 9 to perforated distributing pipes ll) in the bottom of theinner container 2 and extracted from the outer container at a levelbelow the level of the top knife edge of the inner container by means ofthe pipe I2. The pump 1 may be of the variable discharge type whereby tocontrol the rapidity of the flow of the quenching fluid through thecooling coil 8 and thus toaffo-rd control over the temperature at whichsaid fluid is maintained. The provision of the perforated distributingpipes at secures an even distribution of the entering cooled fluid overthe Whole area of the bottom of the inner container 2 and is an aid tomaintaining the quenching fluid at a uniform temperature.

Fixed to the edge of the outer container 3 are a plurality of racks l3for temporarily securing the drills in a vertical position. The rackscomprise a lower horizontal notched member l4 and an upper horizontalmember l5 vertically spaced therefrom which is provided with a pluralityof permanent magnets it so disposed as magnetically to hold the drillsin a vertical position during the quenching operation. As shown, thesaid magnets arespacedso as to provide locating notches ll vertically inline with the notches i 8 in the notched member I l.

The false bottom 4 is preferably a perforated metal plate with groups ofperforations l9 (Fig. 5) arranged at the resting places of the ends ofthe drills 5 thereon and a convenient means for adjusting the plate asregards its level, resides in the provision of a plurality of set screws20 engaging in screw-thread holes therein, and bearing against aplurality of fixed brackets 2| projecting from the inside of the innercontainer 2.

The provision of the inner container 2 being spaced from the outercontainer assists in maintaining the quenching fluid at a uniformtemperature.

What I claim and desire to secure by Letters Patent is:

1. In a quenching bath for hardening and tempering rock drills, meansfor holding and immersing the drills in an inner container comprising aforaminous drill supporting plate removably and adjustably supportedinteriorly of said container upon projections thereon, an'outer overflowcontainer in spaced relation to said inner container, a plurality ofracks secured in spaced relation to one another to said outer containerand extending across and above the inner container, means on said racksfor magnetically holding the drills in spaced relation to one anotherand a member secured to each of said racks having spaced locatingnotches for vertically positioning the drills. j I

2. In a quenching bath for hardening and tempering rock drills, meansfor holding and immersing the drills in an inner container comprising aforaminous drill supporting plate removably and adjustably supportedinteriorly of said container upon projections thereon, an outer overflowcontainer in spaced relation to said inner container, a plurality ofracks secured in spaced relation to one another to said outer containerand extending across and above the inner container, means on said racksfor magnetically holding the drills in spaced relation to one another,said means comprising a plurality of permanent magnets secured inhorizontal alignment and spaced apart to provide a plurality ofmagnetized gaps for receiving the drills, a member secured to each ofsaid racks having a plurality of horizontally spaced locating notches invertical register with the magnetized gaps.

3. In a quenching bath for hardening and tempering rock drills, meansfor holding and immersing the drills in the bath comprising inner andouter stationary containers in spaced relation, means removably andadjustably carried interiorly of the inner container for supporting thedrills, and cooperative magnetic and non-magnetic holding means for thedrills on the outer container.

4. In a quenching bath for hardening and tempering rock drills, meansfor holding and immersing a drill in a container, comprising a drillsupporting plate within said container, a rack extending across andabove'said container and a pair of coacting magnetic elements on saidrack having spaced apart, substantially vertical surfaces adapted togrip therebetween the shank of a drill supported upon said supportingplate, whereby to hold such a drill in asubstantially vertical position.I

5. In a quenching bath for hardening and tempering rock drills, meansfor holding and im-' mersing a drill in a container, according to claim4, further characterized in that the drill supporting plate isadjustable vertically whereby to permit variation of the depth ofimmersion of a drill supported by said plate.

REGINALD ASLINE BEDFORD.

